Origin of abecedary
1570–80; < Late Latin abecedārius (a + be + ce + d(e) + -ārius -ary)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Word Origin and History for abecedary
"primer, alphabet table," mid-15c., from Medieval Latin abecedarium "an ABC book," neuter of adjective abecedarius, used as a noun, from the first four letters of the Latin alphabet. Abecedarian (adj.) is attested from 1660s.
Online Etymology Dictionary, © 2010 Douglas Harper